The European Central Bank bought more German, French and Italian bonds than its rules dictate in May and fell short of its target for smaller countries such as Portugal, Slovakia and Slovenia, data showed on Monday.
The data illustrate the ECB’s growing challenge in following the self-imposed rules of its bond-buying program after it raised its monthly purchases in March, increasing the risk that some smaller countries may benefit less than larger ones from that program.
Bonds of the smaller countries are often harder to find on the market.
And at least in the case of Ireland and Portugal, the ECB is slowing down its purchases to avoid getting close to a limit on how much of the debt of a single country it can own.
Purchases of Portuguese, Slovak, Slovenian and Irish bonds were all below their shares of the so-called ECB capital key.
Cyprus has recently been excluded from the purchases after it left an international rescue program.
Greek bonds have never been bought because of differences between Greece’s government and its lenders, which almost pushed the country out of the eurozone last year.